Indinavir in combination with zidovudine and lamivudine reduces viral load to less than 500 in 85% of patients. The optimal treatment for the 15% who do not respond and for those who have a rebound in viral load is unknown. This randomized, partially blinded, multicenter study will evaluate several drug combinations in patients (50 per arm) who have received indinavir for six months or more and have a viral load greater than 3 2,000 and 2 200,000 copies HIV RNA/mL. The drugs to be studied are the protease inhibitors saquinavir (soft gel capsule) and ritonavir, the reverse transciptase inhibitor delavirdine and the nucleoside analogue adefovir dipivoxil. The primary endpoint of the study will be HIV copy number at 16 weeks. Safety, toxicity and tolerance will also be assessed.